New Jersey’s controversial ballot design that gives party-backed candidates an advantage will be scrapped in the June primary, a federal judge ruled on Friday.

U.S. District Judge Zahid Quraishi granted the preliminary injunction sought by Rep. Andy Kim and two Congressional candidates to eliminate the so-called county line, a feature unique to New Jersey elections that’s given local party bosses inordinate influence over elections. In 19 of 21 counties in the state, candidates backed by county political parties appear in a single column or row, placing them more prominently on the ballot and giving them a nearly insurmountable edge.

The judge ordered the use of office block ballots for the June primary, where candidates are placed together by the office they are seeking. His ruling applies to all offices on the ballot.

The decision is likely to be appealed, but until then it takes away a key tool wielded by political bosses in the state. And while its impact is limited in the Democratic Senate primary since first lady Tammy Murphy has dropped out, it will upend contested primaries across the state — including the House race for the seat held by Democratic Rep. Rob Menendez. His father, Sen. Bob Menendez, is under indictment and will not run in the Democratic primary but is considering an independent run in November if he is not convicted of corruption charges.

The county line — and how it is awarded — became the focal issue in the Democratic primary to replace Menendez. In some parts of New Jersey, a single party boss can award the favorable primary ballot spot while in others, hundreds of low-level party officials vote by secret ballot on who will get the county line.